Nagoya Journal of Medical Science

The lysosome has attracted much attention because of its role in the autolysis of cells, and has suggested the importance of introducing the concept of the lysosome into cancer chemotherapy.
In the present study acid deoxyribonuclease, β-glucuronidase and lysozyme in Yoshida ascites tumor cells were proved to be lysosomal enzym~s because of the high latency in their activities and their characteristic intracellular distribution patterns. However, acid phosphatase was not characteristic in these respects, so that it is not reasonable to estimate the behaviors of lysosomes in Yoshida ascites tumor cells only by the activity of this enzyme.
Since the membranes bounding Iysosomes have been assumed to be lipoprotein in nature, it was investigated whether lipoprotein lipase (LPL) could labilize lysosomes in tumor cells and it was found that LPL could be a strong lysosome labilizer in vitro and in vivo. A combined treatment with LPL and mitomycin.C (MMC) brought more remarkable changes in lysosomes of tumor cells than MMC alone. The membrane stability of lysosomes in tumor cells against LPL was less than that in liver cells of tumor-bearing rats, suggesting no enhancement of toxicity in the combination therapy with LPL and antitumor agents. The survival experiment showed that the cytocidal effect of MMC was etlhanced by LPL.
Based on these experimental findings clinical trials of combination chemotherapy with antitumor agents and lysosome labilizers are under investigation.

A characteristic alteration of hepatic glycogen content by fasting was analyzed about alloxan diabetic rats.
1) In the fed state, hepatic glycogen content was suppressed in alloxan diabetic rats. However, when rats were fasted for 48 hours hepatic glycogen content was higher in alloxan diabetic rats than in the normal ones. There was a positive correlation between the blood glucose level and the liver glycogen level in fasted diabetic condition.
2) When rats were fasted, the incorporation of the blood glucose into both hepatic glycogen and glyceride-glycerol was more in the alloxan diabetic rats when compared with the intact rats. This was calculated from the values of the incorporated [U-^l4C] glucose.
3) On the other hand, under the same condition as 2), the incorporation from [2-^l4C] lactate into liver glycogen was less in alloxan-treated rats. Although ¹⁴C-glucose in the blood converted from (2-^l4C] lactate was more in alloxan-treated rats, it was attributed to delayed disappearance of glucose from the blood stream.